Which of the following methods used to determine the mass of a cluster does not depend on Newton's laws of gravity?
A) measuring the orbital velocities of galaxies in a cluster
B) measuring the temperature of X-ray gas in the intracluster medium
C) measuring the amount of distortion caused by a gravitational lens
D) none of the above
C
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What will be an ideal response?
A runner runs around a track consisting of two parallel lines 96 m long connected at the ends by two semicircles with a radius of 49 m. She completes one lap in 100 seconds. What is her average velocity?
A) 2.5 m/s B) 5.0 m/s C) 10 m/s D) 0 m/s E) 1.3 m/s
An aniline-alcohol solution is flowing at a velocity of 3 m/s through a long, 2.5 cm-ID thin-wall tube. Steam is condensing at atmospheric pressure, on the outer surface of the tube, and the tube-wall temperature is 100°C. The tube is clean, and there is no thermal resistance due to a scale deposit on the inner surface. Using the physical properties tabulated below, estimate the heat transfer coefficient between the fluid and the pipe using and compare the results. Assume that the bulk temperature of the aniline solution is 20°C and neglect entrance effects.
GIVEN
• An aniline-alcohol solution flowing through a thin-walled tube
• Tube is clean with no scaling on inner surface
• Velocity (V) =3 m/s
• Inside diameter of tube (D) = 2.5 cm = 0.025 m
• Tube wall surface temperature (Ts) = 100°C
• Solution has the properties listed above
• Solution bulk temperature (Tb)= 20°C FIND
• The heat transfer coefficient ( ch ) using: (a) Equation (7.61) (b) Equation (7.66)
ASSUMPTIONS
• Steady state
• Entrance effects are negligible
• Thermal resistance of the tube is negligible
• Tube wall temperature is constant and uniform
• Fully developed flow
SKETCH
PROPERTIES AND CONSTANTS
The density of water ? 1000 kg/m3
A highway curve has a radius of 0.14 km and is unbanked. A car weighing 12 kN goes around the curve at a speed of 24 m/s without slipping. What is the magnitude of the horizontal force of the road on the car?
A. 12 kN B. 17 kN C. 13 kN D. 5.0 kN E. 49 kN